Kopera, J. P. The Nashoba Terrane: A new tectonostratigraphy and shared structural styles with the Merrimack belt in Massachusetts. Geological Society of America Abstracts with Programs 47, 42 (2015).

Peck, J. A. Digital conversion of Peck, J.H., 1975, Preliminary bedrock geologic map of the Clinton quadrangle, Worcester County, Mass., U.S. Geological Survey Open File Report 75-658. Digital Conversion (2012).

Castle, R. O., Hepburn, J. C. & Kopera, J. P. [Draft] Preliminary bedrock geologic map of the Lawrence quadrangle, Massachusetts. Open-File Report (2005).

Castle, R. O., Hepburn, J. C. & Kopera, J. P. [Draft] Preliminary bedrock geologic map of the Wilmington quadrangle, Massachusetts. Open-File Report (2005).

Kopera, J. P. Preliminary bedrock geologic map of the Ayer quadrangle, Massachusetts. Open-File Report (2006). at <http://www.geo.umass.edu/stategeologist/>

Kopera, J. P. & Hansen, W. R. Preliminary Bedrock Geologic Map of the Hudson 7.5' Quadrangle Worcester and Middlesex Counties, Massachusetts. Open File Report (2014).

Kopera, J. P. & Hansen, W. R. Preliminary bedrock geologic map of the Hudson quadrangle, Massachusetts. Open-File Report (2005).

Jahns, R. H. & Kopera, J. P. Progress report of bedrock geologic mapping of the Lowell quadrangle, Massachusetts. Progress Map (2010).